a. Field of the Invention
The present invention relates to optical inspection devices and, more particularly, to optical inspection devices for use in pressurized vessels such as pipelines and the like.
b. Description of the Prior Art
In many instances, it is necessary to view the interior of pressurized vessels such as pipelines and the like in order to ascertain whether there has been any damage to particular parts of the pipeline such as orifice plates, or see if there is a clog or debris buildup which can affect accurate metering and/or flow of the pipeline product. For example, it may be necessary to view the interior of a pipeline metering station to determine if any damage or obstructions affect the orifice metering plate. Of course, such inspection cannot be accomplished without various equipment to enable one to remotely view the interior. Also, in cases where the pipeline product may be explosive, due consideration must be accorded potential hazards. Because of this, the prior art has provided various viewing devices.
One such viewing device is disclosed in U.S. Pat. No. 4,777,567 issued to Robert H. Welker et al. on Oct. 11, 1988. The viewing device of the '567 patent utilizes an explosion-proof light projector and viewing periscope particularly for viewing the interior of a gas pipeline metering station. Light from the external light projector is directed into the pipeline through a projector inserted through a bore in the pipeline, while a separate, fixed-depth periscope viewing device extends into the pipeline through a separate bore in the pipeline. The viewing device is not however, adapted for use in high-pressure environments.
Another such prior art viewing device is disclosed in U.S. Pat. No. 4,678,290 issued to Robert H. Welker on Jul. 7, 1987. The '290 viewing device is a fixed depth periscope assembly having an optical system including a lamp sealed therein for a light source. A flow of nitrogen gas is delivered to the battery pack for the lamp and periscope to surround the electrical components for explosion prevention. Again, however, the viewing is at a fixed depth, is not insertable and retractable, nor adapted for high pressure environment use.
Other prior art devices have been used such as endoscopes that rely upon fiber optic light guides for light transmission. However, these devices are not well suited for use in applications where the object to be examined is relatively far away from the viewing scope such as in pipeline applications.
In general, the prior art devices for viewing the interior of vessels including pipelines are not suited for high pressure environments as encountered in active product flowing pipelines, are not insertable or retractable, nor can they retract from their position within the pipeline without being totally removed from the vessel.
Furthermore, such prior art designs cannot, by their nature, take advantage of technologically advanced optic devices or viewing options, as such optic devices could be used to view other spectra or provide digitally capturable images, for example.
It is thus an object of the present invention to provide a variable depth optic device for viewing the interior of pressurized vessels.
It is another object of the present invention to provide an automatically insertable and retractable viewing device for pressurized vessels.
It is further an object of the present invention to provide a variable depth optic device for internal viewing of pressurized pipelines that includes an insertable and retractable viewing head adapted to carry various optic devices.
It is still further an object of the present invention to provide a viewing device that is insertable into and retractable from a pressurized pipeline and which has a viewing head capable of carrying various optic devices and able to withstand high pipeline pressures.